Drink mixers are well known in the art. Typical examples run from the hand-operated egg beater, electrical powered mixers with two egg beaters, or a dough hook, an electrically powered blender such as the type shown in British patent 1,378,240. Devices for making milk shakes or smoothies which have been designed for children include the Baskin-Robbins Shake and Smoothie Swirler, made by Wham-O, this device resembling the blender of the aforementioned British patent. Other variations include the HogWild Mr. Twister, the Easy Bake Smoothie Maker and the Easy Bake Blender. Other prior art mixers include a single shaft mixer of the type shown in U.S. Pat. No. 5,204,263, or a simple shaker of the type shown in U.S. Pat. No. 4,003,555.
In addition to the mixers set forth above, there is another class of mixers which essentially contains a cylindrical container having a lid, there being a reciprocal shaft passing through the lid, the shaft carrying at its lowermost end an apertured disc. Examples of this form of construction are shown in U.S. Pat. Nos. 1,590,831, 2,291,708, 3,589,685, 4,737,036, 4,946,286, 5,327,816, 5,939,122, U.S. design Pat. Nos. 181,143 and 405,642, and British patent GB 237,668. In addition to these drink mixers, butter churns are also known of a similar construction, typical examples being shown in U.S. Pat. Nos. 85,187 and 993,130. In addition to the prior art mentioned above, other devices are known for the purpose of mixing milk with air to form a froth, and these milk frothing devices typically require heating means, usually in the form of steam. An exception is U.S. Pat. No. 5,939,122 which does not require heat.
While the foregoing devices are generally satisfactory for their intended design purposes, they are somewhat limited in their application. Many require electrical power. Others require steam for their operation. Others are too limited in their application. Many of the devices are not robust enough to chop a product such as a banana or melon, and to mix the chopped product with a liquid, such as yogurt. Other devices also lack the required strength for making milk shakes from milk and ice cream or similar products such as frozen yogurt, ice milk, sherbets, or frozen tofu/soy desserts. Other devices are not suitable for use with children because they are easily broken and require a degree of manual dexterity not present in children. Furthermore, these devices may be easily tipped over and their contents spilled.
For example, U.S. Pat. No. 5,939,122 discloses a manually operated milk frothing apparatus which does not require steam, which is required by most prior art milk frothing devices. While this device is suitable for adult use, it has several disadvantages for use with children. Initially, the container is made of glass, which may not be a suitable material for use with children. In addition, the container top can be easily dislodged from the container, and even when in place it will not fully retain the contents of the container if the container should happen to be accidentally knocked on its side. In order to operate the device shown in U.S. Pat. No. 5,929,122 it is necessary to grasp the handle assembly and manually reciprocate it first down and then up. This requires a certain degree of manual dexterity that all children may not possess. The plunger of the above prior art device includes a number of parts which may be disassembled for cleaning, these parts including a bottom plate, a top plate, an annular spring, and a wire mesh screen which is cup shaped. When these parts are disassembled these parts may easily become lost or misplaced. In addition, the wire mesh screen may become bent or distorted in shape to such an extent that it may be difficult to reassemble. Furthermore, the wire mesh screen has fine apertures which easily become clogged, and which does not make the device suitable for a number of products.
Other products have other disadvantages which are overcome by the present invention.